Armature core

ABSTRACT

A moulded armature core comprises a moulded cylindrical block of magnetic material, having a plurality of slots disposed in parallel along the peripheral portion thereof in a manner to extend lengthwise of the block, said slots being so tapered as to progressively decrease in both depth and width.

United States Patent [72] Inventors HarumichiOkamoto;

Kiyoshi Fukui; Teruo Oshima, all 01 Yokohama-shi, Japan [21] Appl.No.871,852

[22] Filed Oct. 28,1969

145 Patented June 22, 1971 {73] Assignee Tokyo Sllibaura Electric Co.,Ltd.

Tokyo, Japan [32] Priority Nov. 2,1968

[S4] ARMATURE CORE 2 Claims, 7 Drawing Figs.

[52] U.S.Cl 310/166, 3101211, 310/265 [51] Int. Cl H02k U26 [50] FieldofSearch 310/261, 264,265,216, 193, 194,211, 166, 179, 180,214,

[56] References Cited UNITED STATES PATENTS 2,662,820 12/1953 Crome75/123 X FOREIGN PATENTS 397,049 2/1966 Switzerland 310/193 575,4135/1959 Canada 310/211 Primary Examiner-D. F. Duggan Attorney-Flynn &Frishauf ABSTRACT: A moulded armature core comprises a mouldedcylindrical block of magnetic material, having a plurality of slotsdisposed in parallel along the peripheral portion thereof in a manner toextend lengthwise of the block, said slots being so tapered as toprogressively decrease in both depth and width.

PATENT-ED JUN22 19m FIG. 2'

FIG. 7

g ARMATURE coma BACKGROUND or THE INVENTION The present inventionrelates to an armature core of an induction motor, and particularly toan armature core formed from magnetic material into a block.

The prior art armature core is constructed by causing many disc platesperforated with slots along the peripheral portion thereof to besuperposed on each other. Since such construction requires manymanufacturing steps and consequently a great deal of time, it has beenproposed that the armature core be formed into a cylindrical block.

SUMMARY OF THE INVENTION An object of this invention is to provide anannature core comprising a cylindrical block of magnetic material and aplurality of slots disposed parallel along the peripheral portion ofsaid block in a manner to extend lengthwise, said slots being so taperedas to progressively decrease in both depth and width.

In this case, said slots may be of a partly closed type. Furthermore,the cylindrical block may be made of ferroalloy consisting of 2.03.5percent carbon, 2.0-3.0 percent silicon and 0.050.l percent manganese,all by weight, and iron and impurities as the remainder. At the time ofalloying said carbon is dispersed in the form of spherulitic graphite.

The features and advantages of this invention will be understood fromthe description with reference to the accompanying drawing.

BRIEF EXPLANATION OF THE DRAWING FIG. 1 is a plan view of an annaturecore according to this invention;

FIG. 2 is a cross-sectional view of said armature core taken along 'aline Il-II of Fig. I;

FIG. 3 is a plan view of another armature core according to thisinvention;

FIG. 4 is a cross-sectional view of said armature core taken along aline lV-IV of FIG. 3;

.FIG. 5 is a side view of an assembly of two annature cores of thisinvention;

FIG. 6 is a cross-sectional view of part of a preliminarily fabricatedcore; and

FIG. 7 is a cross-sectional view of part of a finished core.

DETAILED DESCRIPTIONv OF THE INVENTION FIGS. I and 2 indicate anarmature core embodying this invention. Said armature core consists of acylindrical block 1 of magnetic material such as iron or ferroalloy, anda plurality of slots 2 disposed in parallel along the outer peripheralportion of said block 1 in a manner to extend lengthwise of the block.Each of said slots 2 has a bulb-shaped cross section, so maybe called apartly closed slot. Further, said slot 2 is so tapered as toprogressively decrease in both depth and width. Said cylindrical block 1is easily formed by a simple moulding or diecasting process.

Preferably, said armature core or block is made of ferroalloy consistingof 2.0-3.5 percent carbon, 2.0-3.0 percent silicon and 005-0.] percentmanganese, all by weight, and iron and impurities as the remainder. Atthe time of alloying said carbon is dispersed in the form of spheruliticgraphite. Said armature core can display the same efficiency as that ofthe armature core generally constructed of a plurality of disc platessuperposed on each other.

FIGS. 3 and 4 illustrate another type of armature core of thisinvention. Said armature core consists of a hollow cylindrical block 11of ferroalloy, and a plurality of slots 12 disposed in parallel alongthe inner peripheral portion of said block I]. Said slots 12 are also sotapered as to progressively decrease in both depth and width.

FIG. 5 indicates a combination of two armature cores 21a and 21b. Saidcores 21a and 21b are connected by means of rotor shaft 23, in such amanner that the slots 22a of the core tapered in opposite directions.

In order to form a slot having a bulb-shaped cross section,

' the cylindrical block 1 (11 or 21) is first moulded so as to allow aplurality of U-shaped cross-sectional slots 32 to be integrally formedtherewith, each of which is, of course, so tapered as to progressivelydecrease in both depth and width. Between the adjacent ones of saidslots 32 is defined a longitudinal protrusion 35 which is provided atthe top with a groove 36 having an arched cross section and extendinglengthwise. Then, the cross section of the initially formed slots 32 isreshaped into a bulb-shape by depressing the lateral edges of saidprotrusion by hammering. In this case, the groove 36 permits theprotrusion 35 to be easily depressed.

We claim:

1. A moulded armature core comprising a moulded cylindrical block ofmagnetic material having a plurality of tapered slots disposedsubstantially in parallel along the peripheral both depth and widthalong the length of said block, the

cross section of said slots being dimensionally varied at apredetermined rate in the lengthwise direction of said block; and

a shaft on which said armature cores are mounted such that the slots ofsaid first armature core are displaced a halfpitch with respect to theslots of said second armature core, and such that the slots of saidfirst and second armature cores are tapered in opposite directions.

1. A moulded armature core comprising a moulded cylindrical block ofmagnetic material having a plurality of tapered slots disposedsubstantially in parallel along the peripheral portion of said block andextending lengthwise of said block, said slots being tapered so as toprogressively decrease in both depth and width along the length of saidblock.
 2. An armature assembly for an induction motor comprising: firstand second moulded armature cores each of said armature cores comprisinga moulded cylindrical block of magnetic material having a plurality oftapered slots disposed substantially in parallel along the peripheralportion of said block and extending lengthwise of said block, said slotsbeing tapered so as to progressively decrease in both depth and widthalong the length of said block, the cross section of said slots beingdimensionally varied at a predetermined rate in the lengthwise directionof said block; and a shaft on which said armature cores are mounted suchthat the slots of said first armature core are displaced a half-pitchwith respect to the slots of said second armature core, and such thatthe slots of said first and second armature cores are tapered inopposite directions.